Conventionally, in a dry etching process, a CVD process, or the like in semiconductor manufacturing processes, processing is performed while supplying a large amount of gas in order to perform the processes at high speed. Generally, a turbo-molecular pump that is provided with a turbine blade section and a screw groove pump section is used for evacuating a process chamber in a dry etching process, a CVD process, or the like. When a large amount of gas is discharged in a turbo-molecular pump, frictional heat generated in moving blades (rotor blades) is transmitted from the moving blades to stator blades (stationary blades), spacers, and a base in this order, and then released into cooling water in a cooling pipe disposed on the base.
However, when a larger amount of gas is discharged, the temperature of a rotor that includes the moving blades may disadvantageously exceed an allowable temperature. When the temperature of the rotor exceeds the allowable temperature, the speed of expansion by creep becomes higher. As a result, the rotor may disadvantageously come into contact with a stator within a shorter period than a designed life.
Further, in this kind of semiconductor manufacturing apparatus, a reaction product is generated in etching or CVD, and the reaction product is likely to be accumulated on a screw stator of the screw groove pump section. A gap between the screw stator and the rotor is extremely small. Thus, when the reaction product is accumulated on the screw stator, the screw stator and the rotor may be stuck to each other. As a result, the rotor may not be able to start rotating.
Therefore, in the invention described in Patent Document 1, a turbo-molecular pump is provided with a first cooling water passage which cools rotor blades and a device for regulating the temperature of a screw stator (a heater and a second cooling water passage). The first cooling water passage is disposed on an outer peripheral surface of a pump case, and cools the pump case to thereby cool stationary blades housed inside the pump case. In this manner, providing the first cooling water passage and the temperature regulation device lowers the temperature of the rotor and prevents the accumulation of a reaction product on the screw stator.